*{
    margin: 0;
}
.dibian{
    width: 100%;
    height: 1200px;
    background-color: wheat;
}
.beijing{
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background-color: gray;
    opacity: 0.7;
}
.tankuang{
    width: 30%;
    height: 200px;
    background-color: green;
    position: fixed;
    left: 35%;
    top: 35%;
    opacity: 0.7;
}
.hide{
    display: none;
}
#quxiao{
    position: relative;
    left: 40%;
    top: 40%;
    font-size: 30px;
}
